Cutting machine for fabrics and thermoplastics

ABSTRACT

A cutting machine has a reciprocally driven blade engaged by a guide unit at the free end of the blade. A blade-driving member is fixed above a cutting table on a projecting arm rigidly connected to the table and the guide unit is fixed beneath a plate on the table. Conversely the guide unit can be mounted on the supporting arm and the driving member beneath the plate on the table.

United States Patent Inventor Gunter Stumpf 7421 Mehrstetten, am KreisMunsingen, Germany Appl. No. 5,189 Filed Jan. 23, 1970 Patented Jan. 4,1972 Priority Dec. 2, 1969 Germany P 19 60 473.0

CUTTING MACHINE FOR FABRICS AND THERMOPLASTICS Primary Examiner-James M.Meister Attorney-Waters, Roditi, Schwartz & Nissen 10 Claims, 5 DrawingFigs.

US. Cl 83/171, ABSTRACT: A cutting machine has a reciprocally driven83/527, 83/555, 83/563, 83/647, 83/925 CC blade engaged by a guide unitat the free end of the blade. A Int. Cl B26d 5/08 blade-driving memberis fixed above a cutting table on a pro- Field of Search 83/171, jectingarm rigidly connected to the table and the guide unit is 615, 6, fixedbeneath a plate on the table. Conversely the guide unit 925 C; 7 7 canbe mounted on the supporting arm and the driving member beneath theplate on the table.

PATENIED JAN 41912 SHEET 1 OF 2 iomoi 5 PATENTEU JAN 41972 SHEET 2 BF 2FIG.3

FIGS

CUTTING MACHINE FOR FABRICS AND THERMOPLASTICS FIELD OF INVENTIONBACKGROUND This invention relates to a fabric-cutting machine. Knownmachines employ a continuous band blade for cutting stacks of foldedfabrics and such blade has the advantage that it can be made with smallcross-sectional dimensions e.g., 0.5 8 mm., and it can also neatly cutvery narrow curves and borders. Basically, machines with reciprocatingblades also possess this advantage. However, such machines have hithertobeen designed for manual operation, so that between the fabric carrieror butting table and the operative part of the equipment there has to bea comparatively strong linkage which at the same time also serves as aslide for the cutter blade. Thus the intrinsic advantage of thesmall-dimensioned cutting tool is lost.

The aforementioned advantage of the band blade machines is, however,offset by the following disadvantages: replacement of the band blade, asdesirable for working with a diversified range of materials, can only beeffected with difficulty and much labor; the constructional requirementfor control of the band blade through three or four deflecting pulleys,with necessary protective covers and the size of component parts toabsorb the requisite strains and stresses is disproportionately high.

SUMMARY OF THE INVENTION A fundamental object of this invention is,therefore, to provide a cutting machine which will possess theadvantages of the continuous band machines without, however, havingtheir drawbacks.

A crank drive through crankpins, a driving rod and a crosshead, ascustomarily employed for driving reciprocatory blades, results in theproduction of considerable vibrations in a cantilever design of cuttingmachine due to the unbalanced inertial forces. To prevent the incidenceof such vibrations, the present invention provides a mass in counterdisplacement with the blade, thereby achieving a balance betweenascending and descending massed.

In further accordance with the invention, the blade is supported by adrive means on one side of the cutting table and is guided at the otherside of the table. In order to prevent dragging the topmost folds of apile with the blade during ascent thereof, the blade is transverselyoscillated over a small distance, e.g. 2 mm., the blade moving away fromthe cutting edge during ascent of the blade and returning to the cuttingposition at the top of its stroke. The invention further provides meansto rapidly replace the blade in the drive means and to subsequentlyclamp it in position. There is also provided means to heat the blade forcutting the thermoplastic material. The heating of the bladeadditionally heat seals the cutting edges at the same time as cutting,for instance in woven-style plastics, to prevent fraying. It is alsoeffective for the slitting or separation of sheets with simultaneousheat-seaming of two or more layers at the slit line. The machine alsocomprises means to inactivate the drive means when the blade is heatedsince cutting with heat does not require blade movement.

The invention is based on a cutting machine with a guide unit receivingthe free end of the blade. The machine is characterized according to theinvention by having its driving means fixed above the cutting tablewhich is movable if necessary, preferably on a projecting support armfirmly assembled on the table, the guide unit being fixed underneath thetable. Conversely, the guide unit can be mounted on the support arm andthe driving means beneath the table.

Further details of the invention appear from the following embodiment ofthe invention depicted in the drawing, in which the driving means isfastened on the support arm and the guide unit is fixed beneath thetable. It is clear, nevertheless, that the invention is not altered ifconversely, the guide unit is fitted on the support arm and the drivingmeans is located under the table.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevation view of acutting table with a reciprocating blade cutter on a supporting arm;

FIG. 2 is a section through the blade cutter showing the blade guideadapter under the table;

FIG. 3 is a section taken along line 33 in FIG. 2;

FIG. 4 is a section taken along line 4-4 in FIG. 3; and

FIG. 5 is a section taken along line 5-5 in FIG. 4.

DETAILED DESCRIPTION FIG. 1 shows a cutting machine which comprises adriving means 1 for a reciprocatory cutting blade 2, the driving means Ibeing mounted on a supporting arm 3, having a vertical support sectionsecurely attached to cutting table 4. A control box 5 is mounted on thelong side of the table for adjusting and regulating the driving means 1of the blade 2.

In FIG. 2 the construction of the driving means I is shown in detail. Atthe left end of the horizontal portion of the supporting arm 3, ahousing 6 is fixed containing the constructional elements of the drivingmeans. This includes a V-belt pulley 7 which is mounted on a shaft of aregulatable direct current motor 8. A V-belt 9 engages pulley 7 anddrives a cam member 10, having two eccentric cam elements each of whichis guidably supported in a respective ball bearing. A gudgeon pin 12 onthe right cam element engages in a transverse slot 13 (FIG. 3) at thetop of a slide bar 14 which, as will be explained later, imparts a rapidup and down reciprocatory motion in quick succession to the blade 2which is connected to bar 14.

A gudgeon pin 15 on the left cam element is offset by from gudgeon pin12 and carries a counterweight 16, which moves upward and downward inopposition to slide bar 14.

In FIG. 4 the right longitudinal edge portion of the slide bar is shownwith a tapered end slidably mounted for longitudinal movement in atransversely adjustable lateral guide I7. A similar guide is located atthe other edge of the slide bar 14. Due to the fact that the gudgeon pin12 engages in transverse slot 13 and can transmit only a verticalcomponent of motion to slide bar 14, the otherwise conventionalreciprocating masses required by a driving rod are avoided. Consequentlythe masses are balanced, so that, despite the arrangement of the drivemeans I on arm 3 which is comparatively elongated and cantilevered fromits support, objectionable vibrations cannot accrue.

In order to prevent lifting of the topmost layers of a pile of materialupon the ascent of the blade 2, the invention provides for drawing theblade back slightly, e.g. about 2 mm., from the cutting edge of thematerial before the blade starts its ascent. As shown in FIGS. 2 and 3,this is attained by rigidly linking the top end of the blade 2 to thefront of a regulating cam I8. Cam 18 is pivotally mounted at one end inthe slide bar 14 which moves vertically up and down. The other end ofthe regulating cam terminates in an external lever arm 19, the end ofwhich carries a roller 21 running in a fixed slide block 20, as seen inFIG. 3. During up-and-down movement of bar I4, the regulating cam 18connected to the bar executes an oscillatory movement at the respectiveend-of-stroke positions 22 and 23. The oscillatory movement is effectedabout a center 24, as shown in FIG. 3, through an angle such that blade2 is withdrawn from the cutting edge at the beginning of ascent and thenagain moved toward the cutting edge at the beginning of descent.

In further accordance with the invention the blade 2 is readilyreplaceable and for this purpose the blade 2 is provided with a T-shapedslot 25 at its upper end (FIGS. 2 and 5), by which it is engaged on acorresponding T-shaped anvil piece 26 on a blade holder 27. A tensioningeccentric 28 is provided for clamping the blade tightly against bladeholder 27 by rotating the eccentric after placement of blade 2 on theanvil piece 26. For turning the eccentric, there is provided afour-sided shaft 29 which can be engaged by a socket wrench through anopening 30 (FIG. 2) in the housing 6. Before fastening the blade to thedriving means I, the blade has to be pushed into a friction pulley (tobe described later) located beneath the table 4, for which purposehinged flaps 31 are provided to the right and left of the blade in thetable.

The blade for a table-mounted device is longer than one for a portabledevice and a friction guide roll 32 with a peripheral slot is providedunderneath the table. Roll 32 is electrically insulated, preferably by aceramic insulation sheath 35, from a shaft 34 running in supporting ballbearings 33. A long slot 50 is machined in the blade and opens at thelower end thereof for its insertion into the peripheral slot on the roll32. Thereby, the blade can ride along the roll 32 during itsreciprocatory movement and be guided by said roll.

in addition to cutting textiles, the machine is also intended forthermally cutting plastic fabrics with simultaneous heatsealing of thecut edges, for instance in woven-style plastic fabrics to preventfraying, or in thermally cutting sheets with simultaneous heat-sealingof two or more layers at the place of cut. Therefore according to afurther characteristic of the invention, the blade can be heated bymeans whereby the blade itself act as a thermal resistance unit. Forthis purpose, an insulating guide bar 36, preferably plastic, is mountedboth at the right and left sides of blade 2 beneath the table, each bar36 having a movable circuit terminal 37 secured to a contact disk 38 ofcopper or similar material. When required, the disk 38 can be advancedto contact the blade. The same purpose is served by guide bars 39 withcircuit terminals 40 on the underside of housing 6. Since cutting bymeans of a heated blade does not require any blade motion, switches areoperated by the shifting of the circuit terminals toward the blade so asto prevent any inadvertent starting of driving motor 8. One of theseswitches is shown at 41 at the bottom of housing 6 in FIG. 3. As shownfurther in FIG. 3, circuit terminal 40 connected with power supply 42 ischamfered so that when the terminal 40 is pushed toward the blade,switch 41 becomes operative and disconnects driving motor 8 toinactivate the same. For purposes of easy regulation and control, themotor 8 is a direct current motor.

The elements beneath the table are enclosed by a protective cover 43which is hinged to table 4.

As a source of current for heating the blade is a transformer (notshown) beneath the table which may be low voltage, e.g. 6 volt, anddeliver a high current, eg 250 amps. To regulate the heat output, thetransformer can he stepped over severai stages. Since in the thermalcutting process, the omission of the up-and-down motion of thebladereduces the mechanical strain on the blade to a minimum, it isadvantageous to employ a special blade having the smallest possiblecross sectional area, e.g. 3 sq. mm., so as to keep the amperage low.Here, too, there is the advantage of convenient and easy replacement ofthe blade as previously mentioned.

What is claimed is:

l. A cutting machine comprising a reciprocating blade having a cuttingedge for cutting stacks of fabric or other material, guide means for thereciprocating blade, a cutting table, a projecting supporting armfixedly mounted on said table, a drive unit on said arm, said guidemeans being mounted below the table, said drive unit including a motorsupplying rotary motion, means for converting the rotary motion to apushing motion for the reciprocating blade, said means including avertically reciprocable slide bar guided laterally in said housing andprovided with a transverse groove, a double cam driven by said motor andincluding discs, and pins on the discs, the pin of one of the discsbeing guided in the transverse groove in the reciprocable slide bar, anadjusting cam rotatable in the slide bar and connected with thereciprocating blade, a lever arm connected with the adjusting cam, aroll on said arm, and a slide block in the housing guiding said" rolland having lower and upper stroke end positions and being adapted suchthat on up-and-down movement of the slide bar the adjusting cam swingsat the stroke end positions relative to the slide bar whereby thereciprocating blade is continually reciprocated transversely of thecutting edge in addition to along the same.

2. A machine as claimed in claim comprising means detachably connectinsaid blade to said adjusting cam and comprising a blade ho der, atensioning eccentric carried by said blade holder, said blade holderhaving a T-shaped groove in which said eccentric is slidably inserted,and means engaging said eccentric to clamp the blade tightly againstsaid blade holder.

3. A machine as claimed in claim 1 wherein said means engaging saideccentric comprises a bolt with a turntable shaft accessible via anopening provided in said housing.

4. A machine as claimed in claim 1 wherein said guide means comprises aguide roll having a circumferential groove, said blade being engaged andguided in the circumferential groove of the said guide roll.

5. A machine as claimed in claim 4 comprising a shaft supporting saidguide roll and a ceramic insulation sheath interposed between said shaftand pulley to electrically insulate said guide roll.

6. A machine as claimed in claim 2 comprising means for electricallyheating said blade to effect cutting without movement of said blade, andmeans for inactivating said drive means when the electrical heatingmeans is activated.

7. A machine as claimed in claim 6 wherein said means for electricallyheating said blade comprises means for connecting said blade itself incircuit as a resistance to effect heating thereof.

8. A machine as claimed in claim 7 wherein said means for connectingsaid blade in circuit comprises two sets of displaceable terminals onopposite sides of the blade at spaced locations therealong, saidterminals being coupled to a source of voltage and adapted for contactwith the blade.

9. A machine as claimed in claim 8 wherein one of said sets of terminalsis below said table and the machine further comprises a hinged coverplate covering said one set of terminals.

10. A machine as claimed in claim 1 wherein said drive motor is aregulatable DC motor.

1. A cutting machine comprising a reciprocating blade having a cuttingedge for cutting stacks of fabric or other material, guide means for thereciprocating blade, a cutting table, a projecting supporting armfixedly mounted on said table, a drive unit on said arm, said guidemeans being mounted below the table, said drive unit including a motorsupplying rotary motion, means for converting the rotary motion to apushing motion for the reciprocating blade, said means including avertically reciprocable slide bar guided laterally in said housing andprovided with a transverse groove, a double cam driven by said motor andincluding discs, and pins on the discs, the pin of one of the discsbeing guided in the transverse groove in the reciprocable slide bar, anadjusting cam rotatable in the slide bar and connected with thereciprocating blade, a lever arm connected with the adjusting cam, aroll on said arm, and a slide block in the housing guiding said roll andhaving lower and upper stroke end positions and being adapted such thaton up-and-down movement of the slide bar the adjusting cam swings at thestroke end positions relative to the slide bar whereby the reciprocatingblade is continually reciprocated transversely of the cutting edge inaddition to along the same.
 2. A machine as claimed in claim 1comprising means detachably connecting said blade to said adjusting camand comprising a blade holder, a tensioning eccentric carried by saidblade holder, said blade holder having a T-shaped groove in which saideccentric is slidably inserted, and means engaging said eccentric toclamp the blade tightly against said blade holder.
 3. A machine asclaimed in claim 1 wherein said means engaging said eccentric comprisesa bolt with a turntable shaft accessible via an opening provided in saidhousing.
 4. A machine as claimed in claim 1 wherein said guide meanscomprises a guide roll having a circumferential groove, said blade beingengaged and guided in the circumferential groove of the said guide roll.5. A machine as claimed in claim 4 comprising a shaft supporting saidguide roll and a ceramic insulation sheath interposed between said shaftand pulley to electrically insulate said guide roll.
 6. A machine asclaimed in claim 1 comprising means for electrically heating said bladeto effect cutting without movement of said blade, and means forinactivating said drive means when the electrical heating means isactivated.
 7. A machine as claimed in claim 6 wherein said means forelectrically heating said blade comprises means for connecting saidblade itself in circuit as a resistance to effect heating thereof.
 8. Amachine as claimed in claim 7 wherein said means for connecting saidblade in circuit comprises two sets of displaceable terminals onopposite sides of the blade at spaced locations therealong, saidterminals being coupled to a source of voltage and adapted for contactwith the blade.
 9. A machine as claimed in claim 8 wherein one of saidsets of terminals is below said table and the machine further comprisesa hinged cover plate covering said one set of terminals.
 10. A machineas claimed in claim 1 wherein said drive motor is a regulatable DCmotor.